[ask] Logika Syntax C ini

[Permenkaret]

gan ane baru belajar bahasa pemrograman C nih, tapi ane dah puyeng banget pas mulai-mulai mengenai pointer.







nah program dibawah ini merupakan program untuk merubah infix menjadi postfix gan. mohon bantuannya karna ane bayak yang gak mengerti gan






Spoiler for cekidot:






#include

#include

#include

#include



#define MAX 50



struct infix

{

char target[MAX] ;

char stack[MAX] ;

char *s, *t ;

int top ;

} ;



void initinfix ( struct infix * ) ;

void setexpr ( struct infix *, char * ) ;

void push ( struct infix *, char ) ;

char pop ( struct infix * ) ;

void convert ( struct infix * ) ;

int priority ( char ) ;

void show ( struct infix ) ;



void main( )

{

struct infix p ;

char expr[MAX] ;



initinfix ( &p ) ;



clrscr( ) ;



printf ( "\nEnter an expression in infix form: " ) ;

gets ( expr ) ;



setexpr ( &p, expr ) ;

convert ( &p ) ;



printf ( "\nThe postfix expression is: " ) ;

show ( p ) ;



getch( ) ;

}



/* initializes structure elements */

void initinfix ( struct infix *p )

{

p -> top = -1 ;

strcpy ( p -> target, "" ) ;

strcpy ( p -> stack, "" ) ;

p -> t = p -> target ;

p -> s = "" ;

}



/* sets s to point to given expr. */

void setexpr ( struct infix *p, char *str )

{

p -> s = str ;

}



/* adds an operator to the stack */

void push ( struct infix *p, char c )

{

if ( p -> top == MAX )

printf ( "\nStack is full.\n" ) ;

else

{

p -> top++ ;

p -> stack[p -> top] = c ;

}

}



/* pops an operator from the stack */

char pop ( struct infix *p )

{

if ( p -> top == -1 )

{

printf ( "\nStack is empty.\n" ) ;

return -1 ;

}

else

{

char item = p -> stack[p -> top] ;

p -> top-- ;

return item ;

}

}



/* converts the given expr. from infix to postfix form */

void convert ( struct infix *p )

{

char opr ;



while ( *( p -> s ) )

{

if ( *( p -> s ) == ' ' || *( p -> s ) == '\t' )

{

p -> s++ ;

continue ;

}

if ( isdigit ( *( p -> s ) ) || isalpha ( *( p -> s ) ) )

{

while ( isdigit ( *( p -> s ) ) || isalpha ( *( p -> s ) ) )

{

*( p -> t ) = *( p -> s ) ;

p -> s++ ;

p -> t++ ;

}

}

if ( *( p -> s ) == '(' )

{

push ( p, *( p -> s ) ) ;

p -> s++ ;

}



if ( *( p -> s ) == '*' || *( p -> s ) == '+' || *( p -> s ) == '/' || *( p -> s ) == '%' || *( p -> s ) == '-' || *( p -> s ) == '$' )

{

if ( p -> top != -1 )

{

opr = pop ( p ) ;

while ( priority ( opr ) >= priority ( *( p -> s ) ) )

{

*( p -> t ) = opr ;

p -> t++ ;

opr = pop ( p ) ;

}

push ( p, opr ) ;

push ( p, *( p -> s ) ) ;

}

else

push ( p, *( p -> s ) ) ;

p -> s++ ;

}



if ( *( p -> s ) == ')' )

{

opr = pop ( p ) ;

while ( ( opr ) != '(' )

{

*( p -> t ) = opr ;

p -> t++ ;

opr = pop ( p ) ;

}

p -> s++ ;

}

}



while ( p -> top != -1 )

{

char opr = pop ( p ) ;

*( p -> t ) = opr ;

p -> t++ ;

}



*( p -> t ) = '\0' ;

}



/* returns the priority of an operator */

int priority ( char c )

{

if ( c == '$' )

return 3 ;

if ( c == '*' || c == '/' || c == '%' )

return 2 ;

else

{

if ( c == '+' || c == '-' )

return 1 ;

else

return 0 ;

}

}



/* displays the postfix form of given expr. */

void show ( struct infix p )

{

printf ( " %s", p.target ) ;

}











mohon bantuannya yah gan, dimana lagi ane bisa mencari informasi selain di kaskus

:ceriwislov e: